Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers	$ 537	$ 500	$ 1,660	$ 1,520
Other revenues	22	33	68	87
Operating revenues and other	559	533	1,728	1,607
CNA Financial | Non-insurance warranty
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers	407	399	1,221	1,173
Boardwalk Pipelines | Transportation and storage of natural gas and NGLs and other services
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers	347	329	1,083	1,013
Loews Hotels & Co | Lodging and related services
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers	$ 190	$ 171	$ 577	$ 507